Thermal Management of an Air-Cooled PEM Fuel Cell: Cell Level Simulation

2012 ◽  
Author(s):  
M. Andisheh Tadbir ◽  
S. Shahsavari ◽  
M. Bahrami ◽  
E. Kjeang
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Temperature Distribution ◽  
Thermal Management ◽  
Rejection Rate ◽  
Thermal Design ◽  
Temperature Gradients ◽  
Maximum Temperature ◽  
Cell Level ◽  
Heat Rejection

Air-cooled polymer electrolyte membrane (PEM) fuel cells have recently been the center of attention mainly because of the simplicity they bring into the fuel cell industry. Their main advantage is the elimination of balance-of-plant subsystems such as the liquid coolant loop, heat exchanger, compressor, and air humidifier which greatly reduces the complexity, parasitic power, and cost of the overall system. In air-cooled fuel cells, air is used as a combined oxidant and coolant. However, the net power output is limited by the heat rejection rate and the overall performance and durability are restricted by high temperature gradients during stack operation. An important initial step toward this goal is accurate knowledge of the temperature distribution in the stack in order to optimize heat removal by suitable thermal management strategies. In the present study, a three dimensional numerical model is developed that can predict the temperature distribution in cell level with an acceptable accuracy. Using this methodology, the maximum temperature in the stack as well as temperature gradients, which are two essential operating parameters for air-cooled fuel cells, can be obtained. The model is validated using experimental data for the 1020ACS fuel cell stack from Ballard Power Systems. A parametric study is performed for bipolar plate thermal conductivity and overall thermal characteristics on the cell level to examine the effects of these parameters on the maximum stack temperature, temperature gradient in the cell, and overall heat rejection rate. Based on these results, recommendations are provided for improved thermal design of air-cooled fuel cells.

Effect of the Size of Molten Carbonate Fuel Cells on the Temperature Distribution

2018 ◽  
Vol 773 ◽  
pp. 118-122 ◽  
Author(s):  
Chang Whan Lee ◽  
Jae Hyeong Yu ◽  
Hyun Woo Kim ◽  
Bo Hyun Ryu
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Temperature Distribution ◽  
Gas Flow ◽  
Flow Direction ◽  
Exothermic Reaction ◽  
Maximum Temperature ◽  
Molten Carbonate ◽  
Term Operation ◽  
Molten Carbonate Fuel Cells

Molten carbonate fuel cells (MCFCs) are high-temperature fuel cells that use liquid electrolytes composed of molten carbonates such as Li2CO3, Na2CO3, and K2CO3. Electrochemical reactions of MCFCs are exothermic reaction. Consequently, temperature distribution of fuel cells is one of important factors in long-term operation. In this work, the effects of the size of the fuel cell on the temperature distribution were investigated using CFD analysis. It was found that as the length of the gas flow direction and the number of layers of fuel cell increases, the maximum temperature of the cell was increased.

Thermal Management and Voltage Stabilization in Air-Forced Open-Cathode Fuel Cells

2015 ◽  
Author(s):  
N. Lotfi ◽  
H. Zomorodi ◽  
R. G. Landers
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Thermal Management ◽  
Temperature Control ◽  
Output Voltage ◽  
Voltage Regulation ◽  
Model Uncertainties ◽  
Cell Temperature ◽  
External Disturbances ◽  
Temperature Reference

Temperature control is undoubtedly one of the important challenges in open-cathode fuel cell systems. Due to cost considerations, it is traditionally achieved by constant-speed operation of the fans. In this paper, a state feedback temperature controller, combined with a Kalman filter to mitigate the noisy temperature measurements is designed and implemented. The controller-filter set facilitates robust thermal management with respect to model uncertainties and measurement noise. The proposed temperature control not only manages to track the fuel cell temperature reference, it can also be used to stabilize the output voltage. Voltage regulation is of great importance for open-cathode fuel cells as it guarantees a predictable and fixed fuel cell output voltage for given current values in spite of internal and external disturbances. The controllers were implemented experimentally and the results show promising performances in regulating the reference temperature and voltage despite model uncertainties and disturbances.

scholarly journals Effect of Cell Size on the Performance and Temperature Distribution of Molten Carbonate Fuel Cells

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1361 ◽  
Author(s):  
Jae-Hyeong Yu ◽  
Chang-Whan Lee
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Gas Flow ◽  
High Efficiency ◽  
Cross Flow ◽  
Current Density Distribution ◽  
Maximum Temperature ◽  
Similar Distribution ◽  
Molten Carbonate ◽  
Molten Carbonate Fuel Cells

Molten carbonate fuel cells (MCFCs) are high-operating-temperature fuel cells with high efficiency and fuel diversity. Electrochemical reactions in MCFCs are exothermic. As the size of the fuel cells increases, the amount of the heat from the fuel cells and the temperature of the fuel cells increase. In this work, we investigated the relationship between the fuel cell stack size and performance by applying computational fluid dynamics (CFD). Three flow types, namely co-flow, cross-flow, and counter-flow, were studied. We found that when the size of the fuel cells increased beyond a certain value, the size of the fuel cell no longer affected the cell performance. The maximum fuel cell temperature converged as the size of the fuel cell increased. The temperature and current density distribution with respect to the size showed a very similar distribution. The converged maximum temperature of the fuel cells depended on the gas flow condition. The maximum temperature of the fuel cell decreased as the amount of gas in the cathode size increased.

scholarly journals Micro-Fabricated Thin-Film Fuel Cells for Portable Power Requirements

2002 ◽  
Vol 730 ◽  
Author(s):  
Alan F. Jankowski ◽  
Jeffrey P. Hayes ◽  
R. Tim Graff ◽  
Jeffrey D. Morse
Keyword(s):  
Thin Film ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Thermal Management ◽  
Thin Film Deposition ◽  
Cell System ◽  
Proton Exchange ◽  
Film Deposition ◽  
Portable Power ◽  
Fuel Storage

AbstractFuel cells have gained renewed interest for applications in portable power since the energy is stored in a separate reservoir of fuel rather than as an integral part of the power source, as is the case with batteries. While miniaturized fuel cells have been demonstrated for the low power regime (1-20 Watts), numerous issues still must be resolved prior to deployment for applications as a replacement for batteries. As traditional fuel cell designs are scaled down in both power output and physical footprint, several issues impact the operation, efficiency, and overall performance of the fuel cell system. These issues include fuel storage, fuel delivery, system startup, peak power requirements, cell stacking, and thermal management. The combination of thin-film deposition and micro-machining materials offers potential advantages with respect to stack size and weight, flow field and manifold structures, fuel storage, and thermal management. The micro-fabrication technologies that enable material and fuel flexibility through a modular fuel cell platform will be described along with experimental results from both solid oxide and proton exchange membrane, thin-film fuel cells.

Thermal Simulation of Cooling Channels in Proton Exchange Membrane Fuel Cell

2013 ◽  
Vol 423-426 ◽  
pp. 2091-2097
Author(s):  
Shi Mei Sun ◽  
Wei Liu ◽  
Shi Yao
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Temperature Distribution ◽  
Proton Exchange Membrane ◽  
Heat Dissipation ◽  
Pure Water ◽  
Large Diameter ◽  
Proton Exchange ◽  
Low Velocity ◽  
Cooling Channels

Fuel cells heat dissipation and cooling is a vital part of PEMFC heat management. This paper used pure water as the coolant to control the temperature distribution inside fuel cells. Established cooling channels geometrical model and simulated the temperature distribution in the steady state by using software SINDA/FLUINT. Then discusses the effects of cooling channels branch quantity, diameter and coolant velocity on fuel cell internal temperature distribution, concludes that multi-branch, large diameter pipes and low-velocity coolant make PEMFC work at best conditions.

scholarly journals Dynamic Model for Understanding Spatial Temperature and Species Distributions in Internal-Reforming Solid Oxide Fuel Cells

2012 ◽  
Vol 9 (4) ◽  
Author(s):  
Brendan Shaffer ◽  
Jacob Brouwer
Keyword(s):  
Fuel Cells ◽  
Temperature Distribution ◽  
Solid Oxide Fuel Cells ◽  
Dynamic Model ◽  
Temperature Difference ◽  
Solid Oxide ◽  
Temperature Gradients ◽  
Cell Performance ◽  
Oxide Fuel ◽  
Temperature Differential

Direct internal reformation of methane in solid oxide fuel cells (SOFCs) leads to two major performance and longevity challenges: thermal stresses in the cell due to large temperature gradients and coke formation on the anode. A simplified quasi-two-dimensional direct internal reformation SOFC (DIR-SOFC) dynamic model was developed for investigation of the effects of various parameters and assumptions on the temperature gradients across the cell. The model consists of 64 nodes, each containing four control volumes: the positive electrode, electrolyte, negative electrode (PEN), interconnect, anode gas, and cathode gas. Within each node the corresponding conservation and chemical and electrochemical reaction rate equations are solved. The model simulates the counter-flow configuration since previous research (Achenbach, 1994, “Three-Dimensional and Time-Dependent Simulation of a Planar Solid Oxide Fuel Cell Stack,” J. Power Sources, 49(1), p. 333) has shown this configuration to yield the smallest temperature differentials for DIR-SOFCs. Steady state simulations revealed several results where the temperature difference across the cell was considerably affected by operating conditions and cell design parameters. Increasing the performance of the cell through modifications to the electrochemical model to simulate modern cell performance produced significant changes in the cell temperature differential. Improved cell performance led to a maximum increase in the temperature differential across the cell of 31 K. An increase in the interconnect thickness from 3.5 to 4.5 mm was shown to reduce the PEN temperature difference about 50 K. Variation of other physical parameters such as the thermal conductivity of the interconnect and the rib width also showed significant effects on the temperature distribution. The sensitivity of temperature distribution to heat losses was also studied, showing a considerable effect near the fuel and air inlets. Increased heat transfer from the cell edges resulted in severe temperature gradients approaching 160 K/cm. The dynamic capability of the spatially resolved dynamic model was also demonstrated for a 45% power increase perturbation while maintaining constant fuel and air utilizations.

Fuel Cell Temperature Control With a Precombustor in SOFC Gas Turbine Hybrids During Load Changes

2017 ◽  
Vol 14 (3) ◽  
Author(s):  
Valentina Zaccaria ◽  
Zachary Branum ◽  
David Tucker
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Real Time ◽  
Gas Turbine ◽  
Maximum Temperature ◽  
Inlet Temperature ◽  
System Efficiency ◽  
Temperature Deviation ◽  
Conservation Of Energy ◽  
The Impact

The use of high temperature fuel cells, such as solid oxide fuel cells (SOFCs), for power generation is considered a very efficient and clean solution for conservation of energy resources. When the SOFC is coupled with a gas turbine, the global system efficiency can go beyond 70% on natural gas lower heating value (LHV). However, durability of the ceramic material and system operability can be significantly penalized by thermal stresses due to temperature fluctuations and noneven temperature distributions. Thermal management of the cell during load following is therefore essential. The purpose of this work is to develop and test a precombustor model for real-time applications in hardware-based simulations, and to implement a control strategy to keep constant cathode inlet temperature during different operative conditions. The real-time model of the precombustor was incorporated into the existing SOFC model and tested in a hybrid system facility, where a physical gas turbine and hardware components were coupled with a cyber-physical fuel cell for flexible, accurate, and cost-reduced simulations. The control of the fuel flow to the precombustor was proven to be effective in maintaining a constant cathode inlet temperature during a step change in fuel cell load. With a 20 A load variation, the maximum temperature deviation from the nominal value was below 0.3% (3 K). Temperature gradients along the cell were maintained below 10 K/cm. An efficiency analysis was performed in order to evaluate the impact of the precombustor on the overall system efficiency.

Local Hot Spots of Electric Water Pump Casing Over Various Pumping Loads

2020 ◽  
Author(s):  
Younghyeon Kim ◽  
Yoora Choi ◽  
Sangseok Yu
Keyword(s):  
Temperature Distribution ◽  
Joule Heating ◽  
Hot Spots ◽  
Cooling System ◽  
Hot Spot ◽  
Maximum Temperature ◽  
Water Pump ◽  
Ir Camera ◽  
Heat Rejection ◽  
Electric Water Pump

Abstract The cooling system of an electric vehicle adopts an electric water pump. Since the lifespan of the battery is very sensitive to a very narrow temperature band, the cooling system provides key solutions. The electric water pump is a core component of the cooling system which satisfies performance and durability criteria. Since, a local hot spot of motor casing results in the degradation of motor lifespan, it is necessary to design the motor casing for effective heat rejection. In this study, two different motor casing designs are applied to reject the joule heating of the motor efficiently. The temperature distribution of each casing is investigated with an IR camera. The IR camera was used to identify the local hot spot where the heat was most generated in the pump. Since the joule heating is proportional to pump power, it is necessary to understand the operating characteristics of the electric water pump. The experimental apparatus includes a water reservoir, a bypass valve, pressure and temperature sensors, DAQ, and IR camera. The operating temperature is ranged from atmospheric temperature to 50°C. When the pump is operated with 25°C coolant, each experiment takes 1 hour for the steady-state conditions and maximum temperature up to 55 °C. Three different pump performance are investigated with two different pump casing. The coolant temperature is also changed from 25 °C to 50 °C. As a result, the local hot spot is strongly dependent to pump load and it is mainly observed near the cable connector. Since temperature distribution on the casing surface is also affected by local hot spots, it is necessary to optimize heat rejection by extended surface.

Heat Transfer in an Electromagnetic Bearing

1997 ◽  
Vol 119 (3) ◽  
pp. 611-616 ◽  
Author(s):  
G. F. Jones ◽  
C. Nataraj
Keyword(s):  
Thermal Expansion ◽  
Temperature Distribution ◽  
Dynamic Control ◽  
Thermal Design ◽  
Temperature Gradients ◽  
Time Dependent ◽  
Large Temperature ◽  
Fine Mesh ◽  
Periodic Heat ◽  
Electromagnetic Bearing

An exact solution for two-dimensional, full transient, and steady periodic heat conduction in an electromagnetic bearing is obtained. Classical methods are used to obtain an analytical expression for the temperature distribution that arises from power dissipated in the pole windings. Among the key findings is the need for cooling in the immediate neighborhood of the bearing support due to the relatively large thermal resistance of the supporting structure. The results presented prove the existence of large temperature gradients in the bearing in both the radial and circumferential directions. This demands the need for a fine mesh when performing the commonly used nodal-network thermal analysis. Conditions are described under which the temperature distribution is independent of the frequency of the time-dependent current supplied to the poles. For these cases the problem reduces to steady state, and the solution is given. A peak circumferential temperature difference of about 55°C in the bearing is possible under certain conditions that are discussed. Attention to proper thermal design is critical to reduce the dimensional distortion of the bearing caused by thermal expansion. The effects of thermal expansion can range from catastrophic, should the shaft come in contact with the bearing, to an undesirable change in the force and dynamic control characteristics caused by a variation in the critical shaft-to-bearing clearance, which is of the order of a fraction of a millimeter.

Fuel Cells Constructal Optimization and Research Perspectives

2004 ◽  
Author(s):  
Jose´ V. C. Vargas ◽  
Juan C. Ordonez ◽  
A. Bejan
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
System Architecture ◽  
Global Economy ◽  
Degrees Of Freedom ◽  
Solution Space ◽  
Hydrogen Economy ◽  
Cell Level ◽  
Diffusion Layers ◽  
Research Perspectives

The hydrogen economy is a possible alternative to the current oil based global economy. The technology to build and operate fuel cells is well advanced. However, cost is the reason why fuel cells are not being installed wherever there is a need for more power. Therefore, optimization is a natural alternative to reduce cost and make fuel cells increasingly more attractive for power generation. This paper discusses the process of determining the internal geometric configuration of a unit fuel cell for maximum power. The optimization of construction (architecture) starts at the smallest (elemental) fuel cell level. The optimization of system architecture must be subjected to a fixed volume constraint. There are several degrees of freedom in the fuel cell configuration, i.e., the thickness of two gas channels (fuel and oxidant), two diffusion layers and two reaction layers (anode and cathode) and the electrolyte solution space. Research perspectives for fuel cells are presented and discussed.

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